The purpose of this research project is to develop a sensitive, accurate, and rapid analytical method for analyzing biopsy samples for total selenium content. In recent years, essential trace element imbalances have been found to play crucial roles in certain disease states. Heart and liver disease in humans and animals has, in some instances, been linked to the deficiency or toxicity of the trace mineral selenium. For the purpose of clinical diagnosis and treatment, it is necessary to be able to determine the selenium content in blood serum or tissue specimens, specifically biopsies, with great accuracy and precision. Given the very limited sample size (2 mg), the extremely low concentration of selenium present (200 pg/mg), and the inherent difficulties in analyzing the metalloid elements, the routine analytical methods are insufficiently sensitive or require more sample than is available. The exotic analytical methods are generally unavailable and very expensive. Our proposed solution to the problem of analyzing for selenium in biopsies involves 1) digestion of the tissue specimen in mineral acid, 2) treatment of this digest with an aromatic 1,2-diaminobenzene compound to selectively and quantitatively bind the selenium, forming a piazselenol compound, and 3) extraction of the piazselenol into an organic solvent such as toluene. These three steps effect a separation of selenium from interfering components in the digestion solution, as well as concentrating the selenium in a smaller volume. The toluene solution will then be analyzed by gas chromatography using a very sensitive electron capture detector in one embodiment of the procedure; the alternate procedure would involve using graphite furnace atomic absorption spectroscopy to analyze for the selenium in the toluene solution. From results published in the literature, we feel that these two methods have the necessary sensitivity, speed, and accuracy to accomplish our aim. With reliable values for the selenium content in serum or biopsy samples, medical experts will be better equipped to evaluate the function of this trace element in healthy and diseased patients.